(1) Technical Field
This invention relates to a pivoting actuator used in a head stack assembly (HSA) for a magnetic disk drive, and more particularly, is concerned with improvements in manufacturing and assembly of actuator parts
(2) Description of the Prior Art
The following four documents relate to methods dealing with improvements to a head stack assembly.
U.S. Pat. No. 5,862,019 issued Jan. 19, 1999 to Larson discloses a disk drive actuator assembly adapted for assembly in one of several configurations from a single line of modular components without a manually supervised aligning step.
U.S. Pat. No. 6,091,578 issued Jul. 18, 2000 to Stole. et al. describes disk drive actuator components made of composite material including two layers of fibers orientated in a perpendicular direction relative to each other.
U.S. Pat. No. 6,002,551 issued Dec. 14, 1999 to Goss, et al, discloses a suspension attachment technique and apparatus for attaching suspension to an actuator arm in a disk drive.
U.S. Pat. No. 5,404,636 issued Apr. 11, 1995 to Stefansky, et al, describes a method for assembling a disk drive actuator by inserting a comb device to obtain proper parallelism between stacked drives.
For the past several years, data storage methods has followed a tendency of escalating storage capacity while also shrinking the physical size occupied by its storage capacities. Introduction of ever more powerful computer hardware and software has contributed to increasing market pressures for less expensive, larger capacity and smaller packaging in disk drives. Storage device manufacturers make every effort to achieve any possible incremental cost savings that can be reasonably achieved without loss of technical performance.
The parts and assembly costs for a head stack assembly (HSA) in a magnetic disk drive represent a significant portion of the total cost of the drive apparatus. FIG. 1 illustrates main components of a magnetic disk drive apparatus as conventionally used in present day disk drives. Reference numeral 10 denotes a plurality of magnetic hard disks rotating around an axis 11, and 12 shows an assembly carriage device for positioning each magnetic head slider on a track of each disk. The assembly carriage device 12 is mainly constituted by a pivoting actuator assembly 14 capable of rotating around an axis 13 and a main actuator coil 15 such as for example a voice coil motor for driving the pivoting actuator assembly 14 to rotate. The HSA includes a carriage 14 that is made by machining a suitable material, or by molding or extrusion. Carriage 14 includes one or more suspensions arms represented by the top most suspension arm 16.
Support sections at one ends of a plurality of suspensions 16 are stacked along the axis 13 are attached to the carriage 14, and one or two head gimbal assemblies 17 are mounted on a top section at the other end of each suspension arm 16. Each of the gimbal assemblies 17 has the magnetic head slider mounted at its distal end that the slider opposes to one surface (read and write surface) of each of the magnetic disks 10.
The present invention allows an actuator to be made with fewer parts while reducing the total manufacturing cost by simplifying the assembly operation. Moreover, the present invention reduces tolerances in the actuator assembly while improving drive reliability and robustness.
In present hard disk drive designs, typically a head slider, is positioned by a head stack assembly (HSA) over and under magnetic disks to perform reading and writing of information to the disks. The constituent elements of a standard HSA's include a ball bearing pivot assembly and arms extending across the surfaces of one or more pieces of rotating magnetic media. Typically a head gimbal assembly is positioned at a distal end of each arm. Mounted to the head gimbal is a head slider with a read/write orientation with respect to an associated disk.
In present designs, parts are aligned to each other using external tooling and secured in place with threaded fasteners. Using external tooling to align parts necessitates precision grade tolerances with controlled aligning references. Moreover, the threaded fasteners add increased parts and cost to the actuator assembly, while creating excessively constrained conditions that induce distortions and misalignment of significant parts within the assembly.